Selective control and relative volumes indicator for voice and/or music amplifiers



. INVENTOR.

June 1958 J. c. HILTON SELECTIVE CONTROL AND RELATIVE VOLUMES INDICATOR FOR VOICE AND/0R MUSIC AMPLIFIERS Filed Dec.

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SELECTIVE CUNTROL AND RELATIVE VOLUMES INDIQATGR FOR VOICE AND/GR MUSIC All i- PLIFIERS This invention relates to improvements in control means for voice and music reproducing and amplifying systems, such as the reproduction and amplification of a phonographic or tape recording and direct amplification of voice as transmitted through a microphone, and provides a means whereby music alone, or voice and music in combination are under selective and positive control of the operator, while also providing visual indication and control of the relative volume levels of music and voice to insure a suitably superimposed voice level over that of the music to insure clear reception of the voice, thereby providing an arrangement which is most desirable and useful for dance and music instruction, dances, and entertainments, since, as in a square dance, the music can be reproduced and controlled at the desired volume level with the callers voice superimposed thereon at any desired degree of increase in the volume level, and for announcements the music can be stilled and the voice broadcast, while for round dances and the like and for background music, the music can be broadcast alone.

With this selective control between voice and music as also between volume levels with visual level indications, the unit is suitable for many purposes, and of inestimable value and convenience where selectively in feature and relative volume levels are used.

The objects and advantages of the invention are as follows:

First, to provide means for selective broadcast of voice and/or music, for announcements, dances, instructions, background music, and including selective control of relative volume levels of voice over music.

Second, to provide means as outlined in connection with a conventional main amplifier including reproduction and amplification of recordings and amplification of voice transmitted through a microphone.

Third, to provide volume level control means including visual indications of the apparent volume or the music and the increased volume of the superimposed voice to insure suitable balance between the music and the voice volume levels for perfect reception of the voice.

Fourth, to provide a circuit for the means which is relatively simple and easily connected to and between the respective amplifiers.

in describing the invention reference will be had to the accompanying drawing which illustrates two conventional amplifier circuits in light lines in connection with my selective control means illustrated in heavy lines.

The invention is used in connection with a conventional main amplifier indicated within the dotted outline 10 for reproduction of recorded music indicated at 11 and including amplification, and amplification of voice transmitted through a microphone when connected in the jacks 12, and includes an output transformer 13 and a phonograph volume control 1-1, an input transformer 15 and a source of current 16, which constitute the elements which are connected in circuit with the conventional monitor amplifier which is enclosed within the dotted outline 2i), and with the selective control circuit which States tent constitutes the invention through a multiple contact plug and socket respectively 17 and 13; a sir contact connection being shown, the contacts of which, for purposes of clarity are numbered 1 to 6, connection 3 not being used.

As will be noted, the input or power transformers l5 and 19 of the two amplifiers it) and are connected in paral el to the source of current 16 at and 22, and, 23 and through conductors and 26, connections 1 and 2 of the multiple plug and socket connection and thence through conductors 2'7 and 28, so that both transformers are simultaneously energized by the source of current.

The monitor amplifier 29 has a ground connection 25 in common with the ground of the main amplifier at 30 through conductor 31, contact 6, and conductor 32. The input of the monitor amplifier 2b is connected at 33 with the phonograph volume control stage 1 2- of the main arnplifier as indicated at 35 through conductor 3t), contact 5, and conductor 37.

The output of transformer 13 is connected in circuit at 38 to the visual indicator or voltmeter at 20 through the conductor 41, contact 4 of the multiple plug and socket connection, thence through conductor 42, the other side of the voltmeter being connected to ground through the conductor 44.

The secondary C5 of the output transformer of the monitor amplifier indicated at 56 is biased by a 15 ohm resistor 47, and is provided with an intermediate tap 4-8 which is connected to the intermediate pole d9 of a switch it) which is shown as triple pole double throw. A 7.5 ohm resistor 51 connects from the voice line 4-2 to one of the outer poles of the switch as indicated at 52, the other pole being connected directly to the voice and music line as indicated at 53. One leg of the switch is connected to one terminal of an 8 ohm L-pad indic ted at 55, the other terminal being connected to ground as indicated at Twin loudspeakers 57 and 5%; are connected in series between the adjustable contact arm 5 of the L-pad and ground as indicated at Gil.

The music channel signal of the main amplifier is to a degree fed from an initial srge to the monitor amplifier where the music signal is amplified and fed to the music only pole of the triple pole double throw switch, and through the switch when closed thereto as shown, to the L-pad and thence through the adjustable contact arm 59 to the speaker system for control of the volume level of the music.

When the switch is in the other or dotted position, the full output of the main amplifier is fed directly to the L-pad and thence to the speaker system, with the meter visually indicating the relative volume of the music, and the increased volume developed by the voice.

Thus, by the simple flip of a switch, the output may be changed at will between music only, or voice superimposed on music with control of relative volumes of music and voice.

The loading rewttr -5-7 is provided to place the output transformer to operate under load even when the transformer operation is otherwise interrupted by transicof the circuit through the dotted position of the switch. and thus maintaining the monitor amplifier against damage and free of oscillation.

After all suitable adjustments have been made in the amplifiers, the voltmeter is called into play for indicating the relative volume of the music, the indication of which should read approximately one volt, depending on the desired volume level of music desired. When the voice is added, if there is little increase in the voltage, on viously the voice will not be distinct over the music, therefore the control for the voice should be adjusted to bring the meter reading to somewhere between 2 and 3 volts for good music-voice balance, the best indications for music and voice over music being noted so that the adjustments can be made directly without ascertaining the degree of distinctiveness.

I claim:

Selective control means for music and voice and music from a reproducing and amplifying system comprising a switch including two arms and a plurality of poles, a speaker system including a speaker volume control, and a relative volume indicating meter, a main amplifier having a recording amplification circuit including an input and an intermediate stage with volume control, and a voice amplification circuit and a common output for said circuits, a monitor amplifier having a recording input and having an output transformer, a recording connection from said intermediate stage to said recording input, a recording and voice connection from said common outputto said meter and to one pole of said switch, a connection from said output transformer to a second pole of said switch and a'loacling resistor biasing the secondary of said output transformer for maintaining the circuit under load, a resister in series from said recording and voice connection to a third pole of said switch with one arm of the switch connected to ground and the other connected to the speaker volume control, whereby when the arms of the switch are in one position the speaker system will be in circuit with the monitor amplifier to provide music alone, and when in the other position music will be provided from said common output with the voice superimposed thereon with the indicating meter providing visual indication of the relative volume levels of music alone and with the voice superimposed thereon through normal interruptions of voice broadcast for suitable balance for clear reception of the voice over the music volume level through adjustment of the volume controls.

References Cited in the file of this patent UNITED STATES PATENTS 

